How can I model electricity when data on the residual grid mix is not available?

In GPI version 4.0, and in many PCRs, it is said that option 4 in the electricity modelling hiearchy (electricity consumption mix on the market) shall not be used to model processes over which the manufacturer (EPD owner) has direct control. This means that unless specific electricity has been purchased (demonstrated by a Guarantee of Origin or similar), the residual grid mix has to be used (options 2 or 3 in the hiearchy). However, for some markets, the residual grid mix has not been publicly disclosed. In such cases, how to model the electricity mix depends on the PCR.

For example, as of version 1.3.2, PCR 2019:14 Construction products says that the residual mix may be conservatively estimated by subtracting renewables from the consumption mix on the market. So this is the option that shall be used for processes under the direct control of the EPD owner, in case specific electricity has not been purchased.

For older versions of PCR 2019:14 Construction products, and many other PCRs (including those that do not say anything on the matter, but which follow GPI 4.0), it is instead accepted to use option 4 also for processes over which the manufacturer has direct control (if specific electricity has not been purchased, so that option 1 is not a viable option). 

Furthermore, note that the composition of the residual grid mixes on the market are available for all EU countries and a few additional European countries through the Association for Issuing Bodies (AIB) at https://www.aib-net.org/facts/european-residual-mix.